A single crystal wafer of silicon, sapphire, gallium arsenide, or the like, for manufacturing a semiconductor device is manufactured so as to have a predetermined crystallographical directional property. In the case of the single crystal wafer, since general information on a surface orientation of the wafer is present and a single crystal is well processed, an axis orientation of the wafer may be determined using an X-ray.
A general single crystal wafer has been produced according to standards such as an angle between a surface and a crystal plane of 0±0.5° and 4±0.5°, a horizontal component of a surface orientation of 0.2±0.05°, and a vertical component of a surface orientation of 0±0.1° with respect to a (100) wafer or a (111) wafer. As a usual single crystal wafer usually used as a material of a semiconductor device, a wafer of which a surface normal is tilted with respect to a silicon crystal plane normal by about 0 to 4° is used. Since this angle (a surface orientation, off-cut angle, surface miscut, or surface misorientation) and a direction (an off-cut or miscut direction) in which the surface normal of the wafer is tilted have an effect on a physical property of a manufactured semiconductor device, it is very important to accurately measure the surface orientation. In addition, since this angle and this direction are important factors in determining productivity of the device, they have been importantly controlled in a production line of the wafer for a semiconductor device.
For these reasons, accuracy of an apparatus of measuring and inspecting the surface orientation becomes a decisive factor in determining quality of a product as well as productivity of the production line. Therefore, the apparatus of measuring the surface orientation of the wafer needs to be accurately calibrated before subsequent processing processes such as a polishing process, and the like.
In order to accurately determine an accurate angle formed by the surface normal of the wafer and a vertical axis of the crystal plane and a direction of the angle, a measuring method using an X-ray diffractometer (hereinafter, referred to as an XRD) has been demanded.
Meanwhile, a standard for measuring a crystallographical surface orientation of a single crystal wafer using the XRD has been defined in a standard procedure ASTM F26-87a (Standard Test Method for Determining the Orientation of a Semiconductive Single Crystal). In the ASTM F26-87a standard, which is a standard for measuring a crystallographical orientation of a semiconductive single crystal, a method using an XRD and an optical method have been described. In the method using an XRD, procedures such as an X-ray diffraction theory for measuring an orientation of a semiconductive single crystal, a measuring apparatus, a measuring method, an analyzing method, and the like, has been described.
However, this standard has been described under the assumption that a surface normal of a wafer is the same as a rotation axis of a measuring apparatus. In a general case, since the surface normal of the wafer does not coincide with the rotation axis of the measuring apparatus, a measuring error corresponding to an angle at which they do not coincide with each other is caused. Therefore, in the case in which the surface normal of the single crystal wafer requiring a precise surface orientation is significantly different from the rotation axis of the measuring apparatus, large uncertainty is caused in measuring the surface orientation of the wafer.